What are banned precisely?

If unicycles are banned then presumably the much larger rucksacks
are also banned. If not, why not?

snippity

Ok so you want them banned also?????

I think he mentioned them as a way of highlighting the idiocy of banning
a unicycle...

perhaps you would like to ban
children in peak time? Or guide dogs? What about those pesky other
paying people....you could have a car all to yourself if they weren't
on as well.......

....in the same way as you mentioned that lot to highlight the idiocy of
banning rucksacks.